Hi June!
I hope you had a wonderful 2018, but I know that 2019 is going to be even better as you're ringing in the new yEAR at Epcot!
New Years Eve at Walt Disney World Resort is always a blast as each Disney Theme Park has their own way of celebrating. This is a tough one, because there are pros and cons to each choice. I usually prefer to drive between my "home"
Disney Resort Hotel and Disney's Theme Parks, because I don't like waiting on a bus on even a regular Disney Day. However, tonight is going to be jam-packed no matter what you decide to do as three of Disney's four Theme Parks are open very late. If you take a bus, everyone in your party can safely imbibe to celebrate the new year. Or, if you drive, you might be greeted by a near-capacity, if not already closed, Epcot parking lot.
If this were me, and I'm kind of jealous that it's not, I'd take the Disney Resort Bus as a way to play it safe from the parking lot. Then, to help decrease the wait for a bus when it's time to leave, I'd stay and play well after tonight's New Year's Countdown Fireworks. Epcot is open until 1:00 A.M. tonight (err, tomorrow morning of next yEAR), which means that you can jump in the line of a ride all the way up until 12:59 A.M. Even though the park closes at 1:00 A.M., those who are still in an attraction's queue will still be welcome to soar or drive fast or boat through Arendelle after that time.
A few shops, like Mouse Gears, should be open until at least 1:30 A.M., or you can always walk around the World Showcase and take some night photography. By the time you're done, the bus lines should be more manageable. Disney's Resort Buses will continue to pick guests up from Epcot until 3:00 A.M., so you won't have to rush.
I hope this helped, and Happy New Year, June!
~Kristen